Chris Hermansen wrote:
Peter;The canonical description of DBase files seems to be http://www.clicketyclick.dk/databases/xbase/format/
Well, first of all, I do not know which dBase version is targeted by ArcGIS.Second, I doubt the exact values in http://www.clicketyclick.dk/databases/xbase/format/data_types.html#DATA_TYPES.
From our tests, both dbase III and dBase IV can handle text fields <= 254 characters (and not < 254). Further, dBase III can handle numerics with <= 19 digits and not < 18 digits. dBase IV limits this to <= 20 digits.
The above mentioned tool identifies ArcGIS generated files as dBase IV, in clear conflict on what is said in the above mentioned Wikipedia article.
Cheers, Peter
On Tue, 2009-12-01 at 17:28 +0100, Peter Hopfgartner wrote:Mark Cave-Ayland wrote:Peter Hopfgartner wrote:Dear PostGIS devels,since we right in the middle of comparing interoperability of shape files between some FOSS programs and ArcGIS, we encoutered also the following:gvSIG chokes on the Bigint as produced by pgsql2shp. Looking at ArcGIs generated files, the max length for numbers is 19, compared to 20 for integers and 32 for floating points as in pgsql2shp. This seems to be confirmed by some Borland tools, when configured for dBase III+.Another limit seems to be that of text fields, that must be no longer then 254. This is the maximum as given by ArcGIS and by the Borland tool.Another point is Boolean: ArcGIS seems to not allow the creation of boolean fields and the Borland Tool ("Database Desktop") says that Booleans have a length of 1.Regards, PeterHi Peter,You've brought up some interesting points here. Can you actually clarify these changes with regard to parts of the official shapefile spec, or have they been found purely through experimentation?ATB, Mark.Hi Mark,I do still have to figure out, if there are public specs for this. All I've found is, that attributes should be in data base files which are in dBase format (http://www.esri.com/library/whitepapers/pdfs/shapefile.pdf). From the analysis of the file (and Wikipedia: http://en.wikipedia.org/wiki/Shapefile), it seems that this should be dBase III. I do not have any evidence that there is a public spec for dBase III. So all we did is basically gather some experimental data, where ArcGIS and gvSIG are our references. The first, because ESRI introduced the shape file format and gvSIG, because it is the desktop environment that we encourage our customers to use. Anyway, we have an old Borland/Inprise tool ("Database Desktop") here for managing dBase files and used it for our tests.Peter
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screenshot-dbase-iii.dbf
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screenshot-dbase-iii.DBT
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<<inline: screenshot-dbase-iii.png>>
screenshot-dbase-iv.dbf
Description: application/dbf
<<inline: screenshot-dbase-iv.PNG>>
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